Dr. Kent Brantly and Nancy Writebol are the two Americans currently being flown from Liberia, but it’s not clear which patient will be at Emory, or when they will arrive. Emory is equipped with an isolation unit to treat patients exposed to certain serious infectious diseases. The unit, which is a collab with the CDC, is separate from the other patients and is one of only four such facilities in the country.

At least one of the two will be taken to a hospital at Emory University, near the headquarters of the U.S. Centers for Disease Control and Prevention in Atlanta, hospital officials told CNN’s Dr. Sanjay Gupta.

Brantly and Writebol are described as being in stable-but-grave conditions, with both reportedly taking a turn for the worse overnight, according to statements released Thursday by the faith-based charity Samaritan’s Purse.

There is no known cure or vaccine for Ebola, which the World Health Organization says is believed to have infected 1,323 people in Guinea, Liberia, Sierra Leone and Nigeria between March and July 27.